1. Field of the Invention
The present invention relates to tertiary amine polyamidoamine-epihalohydrin polymers, and to the preparation of tertiary amine polyamidoamine-epihalohydrin polymers.
2. Description of Background and Other Information
Polymers obtained by reacting epihalohydrins with prepolymers prepared from tertiary amines and dicarboxylic acids and/or their derivatives are known in the art. The use of these polymers as wet strength agents for paper is also known.
U.S. Pat. Nos. 4,537,657 and 4,501,862 disclose paper wet strength resins prepared by reacting epihalohydrin with tertiary amine polyamidoamine prepolymers derived from methylbisaminopropylamine with oxalic acid or its ester and urea. A water soluble acid such as hydrochloric acid is added to tertiary amine polyamidoamine prepolymer, in an amount essentially equivalent to the tertiary amines of the tertiary amine polyamidoamine prepolymer; nonhalide acids such as sulfuric, phosphoric, and nitric acids are also taught as being suitable. The pH of the aqueous solution of intermediate is disclosed as usually being adjusted to about 8.5 to about 9.6 before or immediately after the addition of the epihalohydrin. These patents further disclose, in the reaction of epihalohydrin and tertiary amine polyamidoamine prepolymer, the use of sufficient epihalohydrin to convert all tertiary amine groups to quaternary ammonium groups; from about 1 mole to 1.5 moles of epihalohydrin, per mole of tertiary amine of the intermediate, is indicated to be satisfactory. The temperature of the reaction medium is maintained from about 40.degree. C. to about 100.degree. C., until the Gardner-Holdt viscosity of a 25% solids solution at 25.degree. C. has reached about E-F.
U.S. Pat. Nos. 3,311,594 and 3,332,901 disclose wet strength resins prepared by reacting epichlorohydrin with a polyamide, the polyamide being prepared from a polyamine with at least one tertiary amino group and saturated aliphatic dicarboxylic acid. The polyamide is reacted with epichlorohydrin at a temperature of from about 25.degree. C. to about 70.degree. C., until the viscosity of a 20% solid solution at 25.degree. C. has reached about C or higher on the Gardner-Holdt scale. These patents further teach that the reaction may also be moderated by adding acid prior to the addition of epichlorohydrin or immediately after the addition of epichlorohydrin, to decrease the pH usually to pH 8.5-9.5, but in certain instances to 7.5. Corresponding to the teaching of U.S. Pat. Nos. 4,537,657 and 4,501,862, the amount of epichlorohydrin disclosed as being employed is indicated preferably to be sufficient to react with substantially all of the tertiary amine groups. It is further taught that addition of more or less epichlorohydrin is permissible to moderate or increase reaction rates. From about 0.8 mole to about 2.0 moles of epichlorohydrin per mole of polyamide amine is disclosed as being generally contemplated.